This invention relates to improvements in the manufacture of spunbonded nonwoven fabrics, and more particularly to an improved process and system for producing multicomponent spunbond fabric and to the fabrics produced therefrom.
The present invention combines several commercially available filament formation and processing technologies to achieve unique and advantageous product and process characteristics. The invention provides non-woven fabrics with an unexpectedly superior balance of softness, strength, formation and cost. The process for making these fabrics offers flexibility and product design coupled with superior formation and low cost not heretofore provided or suggested in the art.
According to the present invention, a process for producing spunbond nonwoven fabrics is provided, comprising the steps of:
a) separately melting two or more polymeric components;
b) separately directing the two or more molten polymer components through a spin beam assembly equipped with distribution plate configured so that the separate molten polymer components combine at a multiplicity of spinnerette orifices to form filaments containing the two or more polymer components;
c) extruding the multicomponent filaments from the spinnerette orifices into a quench chamber;
d) directing quench air from a first independently controllable blower into the quench chamber and into contact with the filaments to cool and solidify the filaments;
e) directing the filaments and the quench air into and through a filament attenuator and pneumatically attenuating and stretching the filaments;
f) directing the filaments from the attenuator into and through a filament depositing unit;
g) depositing the filaments from the depositing unit randomly upon a moving continuous air-permeable belt to form a nonwoven web of substantially continuous filaments;
h) applying suction from a second independently controllable blower beneath the air-permeable belt so as to draw air through the depositing unit and through the air-permeable belt; and
i) directing the web through a bonder and bonding the filaments to convert the web into a coherent nonwoven fabric.
The present invention also provides a system for manufacturing spunbond nonwoven fabrics. The system includes a combination of the following elements:
a) two or more extruders for separately melting, respectively, two or more polymer components;
b) a spin beam assembly connected to said extruders for separately receiving the molten polymer components therefrom, said spin beam assembly including a spinnerette plate defining a multiplicity of spinnerette orifices, and a distribution plate configured so that the separate molten polymer components combine at the spinnerette orifices to form multicomponent filaments;
c) a quench chamber positioned adjacent to the spin beam assembly for receiving filaments extruded from the spinnerette orifices;
d) a first independently controllable blower mounted for directing air into the quench chamber to quench the molten filaments.
e) an attenuator positioned for receiving the filaments and the quench air and configured for pneumatically attenuating and stretching the filaments;
f) a filament depositing unit;
g) a moving continuous air-permeable belt positioned for having randomly deposited thereon the filaments from the depositing unit to form a nonwoven web of substantially continuous filaments;
h) a second independently controllable blower positioned beneath the air-permeable belt so as to draw air through the depositing unit and through the air-permeable belt; and
i) a bonder for bonding the filaments and to form therefrom a coherent nonwoven fabric.
In a specific embodiment, the initial handling, melting, and forwarding of the two or more polymer components is carried out in respective individual extruders. The separate polymer components are combined and extruded as multicomponent filaments with the use of a spin beam assembly equipped with spin packs having a unique distribution plate arrangement available from Hills, Inc. and described in U.S. Pat. Nos. 5,162,074; 5,344,297 and 5,466,410. The extruded filaments are quenched, attenuated and deposited onto a moving air-permeable conveyor belt using a system known as the Reicofil III system, as described in U.S. Pat. No. 5,814,349. The web of filaments which is formed on the conveyor belt may be bonded, either in this form or in combination with additional layers or components, by passing through a bonder. The bonder may comprise a heated calender having a patterned calender roll which forms discrete point bonds throughout the fabric. Alternatively, the bonder may comprise a through-air bonder. The fabric is then wound into roll form using a commercially available take-up assembly